A 25-year research partnership could provide a significant breakthrough in the safety of explosives. Now, Mining3 is working to bring this new, nitrogen oxide-free formulation to market. LOUIS WHITE reports

Article from resourceful: Issue 10

RESEARCH NEWS

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Since dynamite was discovered in the 1850s, explosives have become accepted industry practice in the extraction of minerals, where they are used to shatter and break rock.

One hundred years or so later, the power of ammonium nitrate (AN) explosives were discovered. AN explosives combined with fuel oil (known as ANFO) have since revolutionised mine blasting.

Explosives were further developed in the 1960s and 1980s with the introduction of AN-based water resistant gel and emulsion products.

But, AN-based explosives have some drawbacks and don't always react efficiently due to a number of uncontrollable and complex factors.

This can sometimes result in the generation of harmful nitrogen oxide fumes (NOx).

"The dominant explosive in the mining arena is based on AN," Mining3 project leader in explosives engineering, Miguel Araos says.

"It is an effective explosive, however, sometimes it produces NOx, which is a harmful fume that comes from the nitrogen present in the AN molecule (NH4NO3)."

Control strategies are used to minimise the risk of NOx hazards, but these rely on personnel.

In a strategic partnership that spans 25 years, Mining3 (formerly CRCMining) and the University of Queensland School of Mechanical and Mining Engineering, are working together on the next generation of explosives to remove the hazard altogether.

The result has been a substitute explosive formulation that does not generate harmful NOx fumes. The team’s new breakthrough formulation eliminates NOx fume emissions by removing the nitrogen and using hydrogen peroxide, as the main oxidiser.

"The initial project was to find the detonation properties of the hydrogen peroxide fuel-based explosives," Mr Araos says. 

"Generally speaking, explosives used in mining detonate with a velocity between 2,000 to 7,000 metres per second. To put this in context, if you were to travel from Sydney to Newcastle – which is approximately 120 kilometres – it would take an explosive anywhere between 18 to 60 seconds to cover that distance."

A key aspect of the project is to understand the velocity, or explosion reach, of the new hydrogen peroxide fuel-based explosives.

"After two years, we have conducted extensive research thanks to funding from the Australian Coal Association Research Program (ACARP)," Mr Araos says.

Another active partner in the development of this new mining explosive has been Solvay, who are an international chemical and advanced materials company. They assist customers in innovating, developing and delivering high-value, sustainable products and solutions, which consume less energy and reduce CO2 emissions.

"The reason we contacted Solvay is that they have a manufacturing plant in Botany, Sydney and are the largest producer of hydrogen peroxide in the world," Mr Araos says.

"While the technology has not been applied yet, we are working with a small company that will put the product in the ground. 

"That will be our learning process to know more about the product. We are confident that we understand the product behaviour at the laboratory scale, but field use is a different beast and we need to tame it."

Another important stage is to conduct testing to determine the product's stability. The geology and ground of every mine is different so there is a need to assess the stability of the product against those conditions.

"Once the stability issue is solved and we have gained enough experience using the product at a small scale, we will be more confident to deploy the technology in the field," Mr Araos says.

"If everything goes well, the product will be trialled on a mine site in 2017."

Mining3 project leader Dr Italo Onederra says that to date more than 160 tests have been conducted to characterise the denotation properties of this new explosive.

"This new technology, which intends to replace part of the ammonium nitrate, could be a step-change for the industry," he says.

"It has the potential to offer different alternatives and possibilities to mining companies."

"The fact that the technology has been developed by us will also provide an independent avenue to conduct explosive and blasting technology research that was previously in the domain of explosive manufacturers."

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